Known electric wires used in high-temperature atmospheres include electric wires whose core wires are coated with any of polyimides, tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymers, and polytetrafluoroethylene.
For example, Patent Literature 1 discloses a heat-resistant insulated electric wire including an insulation layer prepared by applying and sintering a polyimide coating that is obtained by reacting 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, p-phenylenediamine, and 4,4′-diaminodiphenyl ether.
Patent Literature 2 discloses an electric wire including a polytetrafluoroethylene coating wherein the coating body partially includes a stripe of another polytetrafluoroethylene having different properties in the longitudinal direction.
Patent Literature 3 discloses a coated electric wire including a core wire coated with a molded tetrafluoroethylene copolymer including tetrafluoroethylene and a perfluoro(alkyl vinyl ether), wherein the copolymer has 10 to 100 functional groups per 106 carbon atoms, with the number of —COF and/or —COOH among the functional groups being 10 to 100 in total per 106 carbon atoms.